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1.
陈丹  郭玉金  杨梦琦  蔡骅琳  江沛 《金属学报》2018,23(12):1425-1430
血管紧张素(1-7)[angiotensin(1-7),Ang(1-7)]通过肾素-血管紧张素系统(renin-angiotensin system,RAS)新的作用分支血管紧张素转化酶2(angiotensin-converting enzyme 2,ACE2)-血管紧张素(1-7)-Mas受体(ACE2-Ang(1-7)-Mas)轴反向调节经典ACE-AngII-AT受体轴。Ang(1-7)广泛存在于下丘脑视上核和室旁核,可以通过缓激肽、一氧化氮合酶(NOS)、环氧合酶(COX)及一些信号通路影响其他中枢神经递质的合成及释放,发挥扩张血管、抗心律失常、抗炎等作用,达到保护心血管及中枢神经系统的效果。本文就Ang(1-7)的分布及在中枢神经系统中多样性的生物功能作一综述。  相似文献   
2.
在传统一维漏磁检测的基础上,为了获取更多特征信息以提高漏磁检测对缺陷的识别能力,提出了三维漏磁检测新方法.较传统一维检测,三维漏磁检测对信号采集系统有着更高的要求,本文适时提出了一种适应三维漏磁检测的磁场测量探头的设计方案,并已经在实验现场得到应用.  相似文献   
3.
针对目前机电一体化专业机电综合性实验相对薄弱的问题,构建基于PMAC运动控制器的开放式数控实验教学平台.在此基础上进行伺服随动控制、控制系统校正环节设计、机电系统控制性能分析等实验教学工作,加深了数控实验教学内容,改善了机电综合实验和相关课程的教学效果.  相似文献   
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Sprague-Dawley rats were exposed to 0.8 ppm ozone (O3), to 14.4 ppm nitrogen dioxide (NO2), or to both gases simultaneously for 6 h per day for up to 90 d. The extent of histopathologic changes within the central acinus of the lungs was compared after 7 or 78 to 90 d of exposure using morphometric analysis by placement of concentric arcs radiating outward from a single reference point at the level of the bronchiole- alveolar duct junction. Lesions in the lungs of rats exposed to the mixture of gases extended approximately twice as far into the acinus as in those exposed to each individual gas. The extent of tissue involvement was the same at 78 to 90 d as noted at 7 d in all exposure groups. At the end of exposure, in situ hybridization for procollagen types I and III demonstrated high levels of messenger RNA within central acini in the lungs of animals exposed to the combination of O3 and NO2. In contrast, animals exposed to each individual gas had a similar pattern of message expression compared with that seen in control animals, although centriacinar histologic changes were still significantly different from control animals. We conclude that the progressive pulmonary fibrosis that occurs in rats exposed to the combination of O3 and NO2 is due to sustained, elevated expression of the genes for procollagen types I and III. This effect at the gene level is correlated with the more severe histologic lesions seen in animals exposed to both O3 and NO2 compared with those exposed to each individual gas. In contrast, the sustained expression of the procollagen genes is not associated with a shift in the distribution of the lesions because the area of change in each group after 7 d of exposure was the same as after 78 to 90 d of exposure.  相似文献   
6.
The role of ensheathing cells, a macroglial cell type with a unique presence in the olfactory system, in the outgrowth of olfactory receptor cell neurites was explored in vitro. Glial cell cultures harvested from both the olfactory bulb nerve layer and the hippocampus were established and immunocytochemically characterized. The expression of the p75 low-affinity nerve growth factor receptor by ensheathing cells was used to distinguish them from other macroglial subpopulations. Results indicated that ensheathing cell cultures were approximately 80% pure. Olfactory receptor cells were cocultured with ensheathing or hippocampal glial cells or were seeded on laminin or poly-L-lysine as controls. Olfactory receptor cells extended the longest primary neurites when cocultured with ensheathing cells. Neurite extension on hippocampal glia and laminin was less extensive than that observed on ensheathing cells but higher than that on poly-L-lysine. The neurite outgrowth-promoting effect of ensheathing cells was, at least in part, mediated by diffusible factors, because olfactory receptor cell neurite extension could also be facilitated when receptor cells were cultured in ensheathing cell-conditioned media. In contrast, cortical neurons extended neurites of equivalent lengths on ensheathing and hippocampal glia. The results suggest that ensheathing cells may release factors that support the continuous outgrowth of olfactory receptor cell axons and, therefore, the capacity of this pathway to recover from injury.  相似文献   
7.
A molecular model was built for human lecithin:cholesterol acyltransferase (LCAT) based upon the structural homology between this enzyme and lipases (Peelman et al. 1998. Prot. Sci. 7: 585-597). We proposed that LCAT belongs to the alpha/beta hydrolase fold family, and that the central domain of LCAT consists of a mixed seven-stranded beta-pleated sheet with four alpha-helices and loops linking the beta-strands. The catalytic triad of LCAT was identified as Asp345 and His377, as well as Ser181. This model is used here for the interpretation of the structural defects linked to the point mutations identified in LCAT, which cause either familial LCAT deficiency (FLD) or fish-eye disease (FED). We show that these mutations occur in separate domains of the 3D structure of the enzyme. Most mutations causing familial LCAT deficiency are either clustered in the vicinity of the catalytic triad or affect conserved structural elements in LCAT. Most mutations causing fish-eye disease are localized on the outer hydrophilic surface of the amphipathic helical segments. These mutations affect only minimally the overall structure of the enzyme, but are likely to impair the interaction of the enzyme with its co-factor and/or substrate.  相似文献   
8.
Basophils stimulated with IL-3 plus C5a selectively express IL-4 and IL-13 and continuously produce leukotrienes (LT) for hours. C5a combined with IL-5 or granulocyte-macrophage colony-stimulated factor was, however, much less effective in promoting cytokine expression and a late continuous phase of LTC4 production, possibly due to lower expression levels of their receptor alpha chains. Basophils also express several chemoattractant receptors, including high levels of C5a receptors, macrophage chemotactic protein (MCP) receptors (CCR2) and eotaxin receptors (CCR3), intermediate levels of CXCR1, CXCR2 and platelet-activating factor receptors, and lower levels of N-formyl-Met-Leu-Phe (fMLP) receptors. However, among the corresponding agonists, only C5a, fMLP and much more weakly MCP1, were found to induce cytokine expression and continuous LTC4 release, and only when combined with IL-3. CCR3, which is highly expressed on basophils and has been shown to mediate strong migratory but weak release responses, does not regulate cytokine expression. The weakly expressed fMLP receptor is an efficient activator of several cell functions including LTC4 formation, while CXCR2 hardly affects basophil function despite considerable expression. Thus, chemoattractant-receptors mediate different cellular responses unrelated to their expression levels.  相似文献   
9.
The optic disk-directed growth of retinal ganglion cell axons is markedly disturbed in the presence of polyclonal antineurolin antibodies, which mildly affect fasciculation (Ott, H., M. Bastmeyer, and C.A.O. Stuermer, 1998. J. Neurosci. 18:3363-3372). New monoclonal antibodies (mAbs) against goldfish neurolin, an immunoglobulin (Ig) superfamily cell adhesion/recognition molecule with five Ig domains, were generated to assign function (guidance versus fasciculation) to specific Ig domains. By their ability or failure to recognize Chinese hamster ovary cells expressing recombinant neurolin with deletions of defined Ig domains, mAbs were identified as being directed against Ig domains 1, 2, or 3, respectively. Repeated intraocular injections of a mAb against Ig domain 2 disturb the disk-directed growth: axons grow in aberrant routes and fail to reach the optic disk, but remain fasciculated. mAbs against Ig domains 1 and 3 disturb the formation of tight fascicles. mAb against Ig domain 2 significantly increases the incidence of growth cone departure from the disk-oriented fascicle track, while mAbs against Ig domains 1 and 3 do not. This was demonstrated by time-lapse videorecording of labeled growth cones. Thus, Ig domain 2 of neurolin is apparently essential for growth cone guidance towards the disk, presumably by being part of a receptor (or complex) for an axon guidance component.  相似文献   
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